Component: Throw exception in case of signal method in Component or P…

…resenter is private [Closes #263]

src/Application/UI/Component.php

@@ -103,7 +103,10 @@ protected function tryCall(string $method, array $params): bool
 		$rc = $this->getReflection();
 		if ($rc->hasMethod($method)) {
 			$rm = $rc->getMethod($method);
-			if ($rm->isPublic() && !$rm->isAbstract() && !$rm->isStatic()) {
+			if ($rm->isPrivate()) {
+				throw new Nette\InvalidStateException('Method ' . $rm->getName() . '() can not be called because it is private.');
+			}
+			if (!$rm->isAbstract() && !$rm->isStatic()) {
 				$this->checkRequirements($rm);
 				try {
 					$args = $rc->combineArgs($rm, $params);